## 19.11. Using Word-Abbreviation Mode

Like vi, Emacs provides an "abbreviation" facility. Its traditional usage lets you define abbreviations for long words or phrases so you don't have to type them in their entirety. For example, let's say you are writing a contract that repeatedly references the National Institute of Standards and Technology. Rather than typing the full name, you can define the abbreviation `nist`. Emacs inserts the full name whenever you type `nist`, followed by a space or punctuation mark. Emacs watches for you to type an abbreviation, then expands it automatically as soon as you press the spacebar or type a punctuation mark (such as `.`, `,`, `!`, `?`, `;`, or :).

One use for word-abbreviation mode is to correct misspellings as you type. Almost everyone has a dozen or so words that he habitually types incorrectly, due to some worn neural pathways. You can simply tell Emacs that these misspellings are "abbreviations" for the correct versions, and Emacs fixes the misspellings every time you type them. If you take time to define your common typos as abbreviations, you'll never be bothered with `teh`, `adn`, and `recieve` when you run the spellchecker. Emacs sweeps up after your typos and corrects them. For example, let's say that you define `teh` as an abbreviation for `the`. When you press the spacebar after you type `teh`, Emacs fixes it immediately, and you continue happily typing. You may not even notice that you typed the word wrong before Emacs fixes it.

### 19.11.1. Trying Word Abbreviations for One Session

Usually, if you go to the trouble of defining a word abbreviation, you will use it in more than one Emacs session. But if you'd like to try out abbreviation mode to see if you want to make it part of your startup, use the following procedure to define word abbreviations for this session:

1. Enter word-abbreviation mode by typing ESC-x `abbrev-mode`. `abbrev` appears on the mode line.

2. Type the abbreviation you want to use, and press CTRL-x `a`. Emacs then asks you for the expansion.

3. Type the definition for the abbreviation, and press RETURN. Emacs then expands the abbreviation; it will do so each time you type it followed by a space or punctuation mark. The abbreviations you've defined will work only during this Emacs session.

If you find that you like using word-abbreviation mode, you may want to make it part of your startup, as described in the following section.

### 19.11.2. Making Word Abbreviations Part of Your Startup

Once you become hooked on abbreviation mode, make it part of your .emacs file so that you enter abbreviation mode and load your word-abbreviations file automatically. To define word abbreviations and make them part of your startup:

1. Add these lines to your .emacs file:

   >     (setq-default abbrev-mode t)
   >     (read-abbrev-file "~/.abbrev_defs")
   >     (setq save-abbrevs t)

2. Save the .emacs file, and re-enter Emacs. `Abbrev` appears on the mode line. (You'll get an error at this point; ignore it -- it won't happen again.)

3. Type an abbreviation you want to use, and then type CTRL-x `a` following the abbreviation. Emacs asks you for the expansion.

4. Type the definition for the abbreviation, and press RETURN. Emacs expands the abbreviation and will do so each time you type it followed by a space or punctuation mark. You can define as many abbreviations as you wish by repeating Steps 3 and 4.

5. Type ESC-x `write-abbrev-file` to save your abbreviations file. Emacs asks for the filename.

6. Type `~/.abbrev_defs`. Emacs then writes the file. You need only take this step the first time you define abbreviations using this procedure. After this file exists, the lines in your .emacs file load the abbreviations file automatically.

After you've followed this procedure the first time, you only need to use Steps 3 and 4 to define more abbreviations. When you add word abbreviations in subsequent sessions, Emacs asks whether you want to save the abbreviations file. Respond with a `y` to save the new abbreviations you've defined and have them take effect automatically. If you define an abbreviation and later regret it, use ESC-x `edit-word-abbrevs` to delete it.

-- DC

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